File Name: defects of human eye and their correction .zip
It is an optical instrument just like a photographic camera. It forms the real image of the object on retina of the eye.
Sometimes, the eye may gradually lose its power of accommodation. Computer vision detection of defective apples using automatic. Below are given the nature of the defect, its causes and corrective measures.
Defects of Vision
Question 1 What is myopia? State the two causes of myopia? Question 5 What are the two common defects of vision? Question 6 What type of spectacles should be worn by a person having the defects of myopia and hypermetropia?
Question 7 What is presbyopia? Write two causes of this defects? Question 8 What is cataract? How is the vision of a person having cataract restored? Question 9 What are the advantages of having two eyes instead of just one? Question 10 What precautions should be taken while donating eyes?
The ability to see is called vision. It is also called eyesight. There are three common defects of vision or defects of eye. These lenses are usually used in the form of eye- glasses or spectacles. The defect of eye called myopia or short-sightedness is caused. The far point of eye having myopia or short-sightedness is at point F which is less than infinity.
The parallel rays of light coming from the distant object O at infinity are converged to form an image I in front of the retina due to which the eye cannot see the distant objects clearly. The image is formed in front of the retina either due to high converging power of eye-lens or due to eye-ball being too long.
The far point of eye having myopia is at point F which is less than infinity. If the distant object can be made to appear as if it were at the far point F of this eye, then the eye can see it clearly.
This is done by putting a concave lens in front of the eye. Myopia is corrected by using spectacles containing concave lenses. When a concave lens L of suitable power is placed in front of the myopic eye. Then the parallel rays of light coming from the distant object are first diverged by the concave lens.
The focal length of concave lens needed to correct myopia or short-sightedness in a person is calculated by using the lens formula:. The defect of eye called hypermetropia or long- sightedness is caused. The image is formed behind the retina either due to low converging power of eye- lens or because of eye-ball being too short.
Because of this an old person cannot see the nearby objects clearly. Cataract decreases the vision of the eye gradually. Advantages of having two eyes are:. All the predators like tiger, lion, etc. Some of the important points to be noted about the donation of eyes are the following:. University and has many years of experience in teaching. Thanks , it really of great help. I found it simpler to understand. My pre medical physics will has really be so easier now in relation to the eyes defects and correction.
I will be grateful if you help me on the function and structure of the eye. Thanks a lot for you educational support through this website. By reading with comprehensive method I was strong enough to do my assignment. Ah this is really great. God will continue to bless and strengthen you. Your email address will not be published. Contents 1 Defects of vision and their correction 2 Myopia Short-sightedness or Near-sightedness 3 1 Due to high converging power of eye-lens because of its short focal length 4 2 Due to eye-ball being too long 5 Myopia short-sightedness or near-sightedness is corrected by using spectacles containing concave lenses.
Comments Tq so much it is very useful and also easy to under stand. It has been of help to me. Leave a Reply Cancel reply Your email address will not be published.
Defects of Vision and their Correction
Refractive eye defects can also be corrected using contact lenses or through specific surgical procedures. Youtube - Hindi. The far point for the myopic eye is nearer than infinity Occurs due to Excessive curvature of the eye lens Elongation of eyeball The image of a distance object is formed in front of the retina and not on the retina Defected is corrected by using Concave lenses such that the lens will bring the image back on to the retina. Hypermetropia Far sightedness : A person with Hypermetropia can see faraway objects clearly. A person with Hypermetropia cannot see nearby objects clearly. Focal length of the eye lens is too long Eyeball has become too small. The image of a distance object is formed in behind the retina and not on the retina Defected is corrected by using Convex lenses such that the lens will bring the image back on to the retina.
Below are given the nature of the defect, its causes and corrective measures Nearsightedness , also called myopia is a common name for impaired vision in which a person sees near objects clearly while distant objects appear blurred. In such a defective eye, the image of a distant object is formed in front of the retina and not at the retina itself. Consequently, a nearsighted person cannot focus clearly on an object farther away than the far point for the defective eye. This may arise due to either. This defect can be corrected by using a concave diverging lens. A concave lens of appropriate power or focal length is able to bring the image of the object back on the retina itself.
Search this site. Home Introduction: How do eyes work? The three vision defects Defects of Vision and their Correction References. Defects of Vision and their Correction. How do eyes work? The three vision defects.
Defects of vision and their correction pdf
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